The present invention relates to an organic carrier containing active substances for influencing plant growth and to a process for producing and using the same.
Plastic sheets are finding increased use in agriculture and horticulture for promoting growth and protecting crops. For example, perforated cover sheets have gained significant use in growing early vegetables and mulch sheets are used in cultivating corn and strawberries. By covering the plants, a microclimate is created under the sheets which, during the cold season in the spring, has noticeably higher temperatures than the uncovered surroundings and thus promotes growth. Simultaneously with promoting plant growth, however, the growth of undesirable weeds is encouraged. These weeds compete with the cultivated plants for light and nourishment, and prevent their proper development. Therefore, the weeds must be eliminated. In addition, fungus diseases such as powdery mildew and the like, as well as early damaging insects such as the cabbage maggot and the like, thrive in this humid and warm microclimate and must also be eliminated.
At present, insects and weeds are controlled by applying the necessary plant protection agents to the field before the sheets are applied, for example, by spraying solutions or dusts, and the sheets are then installed. Subsequent insect and weed control, after application of the sheets, is no longer possible. If one nevertheless desires to apply such agents, it becomes necessary to remove and reinstall the sheets, which makes the process uneconomical.
The period during which the cultivated plants are covered is generally two to three months. That means that the effect of the insect and weed control agents must be adapted to this period. With a one-time application before application of the sheets, the quantity of active substances must be selected to be correspondingly high to be effective over this long period of time without subsequent applications. However, excess quantities used in the application are subject to leaching, since weed killers and insecticides are water soluble to a certain extent. This results in the known problems of contaminating the soil and the groundwater and streams from which drinking water is obtained.